JPS63163839A - Exposing device - Google Patents

Abstract

PURPOSE:To prevent the quantity of light from decreasing owing to a rise in temperature and to obtain a necessary quantity of light at all times by stopping the light irradiation of a light source during backward exposure scanning when the temperature of the light source exceeds a specific value. CONSTITUTION:This device has the light source 4 which projects light on a body to be read, a heater 40 which heats the light source, a detecting means (thermistor) 45 which detects the temperature of the light source, and a stopping means (exposure lamp control circuit) 33 which stops the light irradiation of the light source during backward exposure scanning when the temperature of the light which is detected by the detecting means exceeds a specific value. Then the temperature of the light source which is heated by the heater is detected by the detecting means and when the detected temperature of the light source exceeds the specific value, the light irradiation of the light source is stopped by the stopping means during the backward exposure scanning. Consequently, a rise in the tube wall temperature of the light source by its self-heating can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an exposure method applied to, for example, an electronic copying machine.

(Prior Art) As is well known, an electronic copying machine is equipped with an exposure device having an exposure lamp (light source), and the image of the document is read by lighting the exposure lamp and exposing and scanning the surface of the document. It looks like this.

In such an exposure apparatus, a fluorescent lamp is used as an exposure lamp.

However, in exposure equipment that uses fluorescent lamps, the tube wall temperature of the fluorescent lamp must be set at a predetermined temperature (limit temperature)! ! A heater (heating means) is wrapped around the fluorescent lamp. In other words, as shown in Figure 5, a fluorescent lamp has a power of about 20
The optical layer is significantly reduced at low temperatures of about 60° C. or below and at high temperatures of about 60° C. or above. Therefore, in order to always obtain a predetermined amount of light, the tube wall temperature of the fluorescent lamp is controlled by a heater.

However, in exposure apparatuses that use fluorescent lamps, the fluorescent lamps are turned on not only during forward movement but also during backward movement when scanning a document. For this reason, when the temperature of the tube wall rises above the limit temperature due to self-heating of the fluorescent lamp, it is not possible to obtain a required predetermined light layer.

(Problems to be Solved by the Invention) In this invention, the fluorescent lamp is turned on when scanning a document and also during the return movement, so that the temperature of the tube wall exceeds the limit temperature due to the self-heating of the fluorescent lamp. To provide an exposure device which eliminates the drawback that the required amount of light cannot be obtained when the temperature is raised, prevents the decrease in the amount of light due to a rise in temperature, and can always obtain the required amount of light. With the goal.

[Structure of the Invention] (Means for Solving the Problems) The exposure apparatus of the present invention includes a light source that irradiates light onto an object to be read, heating means that heats the light source, and detects the temperature of the light source. and a stop means that stops light irradiation from the light source during the return movement of exposure scanning when the temperature of the light source detected by the detection means exceeds a predetermined value.

(Function) This invention detects the temperature of the light source heated by the heating means with a hand, and when the temperature of the detected light source exceeds a predetermined value, the light irradiation from the light source is reversed in the exposure scan. By stopping the light source with a stop means, an increase in tube wall temperature due to self-heating of the light source is suppressed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

2 and 3 schematically show an image forming apparatus, for example, a two-color copying machine. That is, 1 is a main body of a copying machine, and a document table (transparent glass) 2 is fixed to the upper surface of the main body 1 for supporting a document (an object to be read). This document table 2 has a fixed scale 2 that serves as a reference for setting the document.
1 is provided, and a document cover 11 that can be opened and closed is provided near the document table 2.

The original placed on the document table 2 is moved by an optical system consisting of an exposure lamp (fluorescent lamp) 4 as a light source and a mirror 5°6.7 along the lower surface of the document table 2 in the direction of arrow a. By doing so, exposure scanning is performed during the forward movement. In this case, mirror 6.7 moves at half the speed of mirror 5 so as to maintain the optical path length. The light reflected from the original by the scanning of the optical system, that is, the light reflected from the original by the light irradiation of the exposure lamp 4, is reflected by the mirror 5.6.
7, passes through the variable magnification lens block 8, is roughly reflected by mirrors 91, 92, and 93, and is guided to the photoreceptor drum (078 mm) 10, where the image of the original is displayed on the surface of the photoreceptor drum 10. It is designed to be imaged.

The photosensitive drum 10 rotates in the direction shown by the arrow at the same speed as the scanning speed of the original by the optical system, and the surface is first charged by the charging device 11, and then the image is exposed by slit exposure at the exposure section Ph. As a result, an electrostatic latent image is formed on the surface. This static N latent image contains, for example, red toner, which is rarely used, and black toner, which is frequently used. It is designed to be visualized by being attached.

That is, the above 1. The second developing device 121° 122 is
It is designed to be selectively driven in accordance with the operation of a color change (developing device selection) key 30a on an operation panel 3o provided on the copying machine main body 1. As a result, in normal times, the electrostatic latent image formed on the photoreceptor drum 10 by the developing device 122 is developed with black toner, and when specifying a color using the color change key 30a, the developing device 122
As a result, the electrostatic latent image formed on the photoreceptor drum 10 is developed with red toner.

In this case, for example, in normal times, the toner on the exposed portion of the sleeve constituting the developing device 121 is scraped off by a blade (none of which is shown) provided on the sleeve, so that the red toner does not come into contact with the photoreceptor drum 10. When specifying a color, the toner on the exposed part of the sleeve constituting the developing device 122 is scraped off by a blade (none of which is shown) provided on the sleeve, and the black toner is applied to the photoreceptor drum 10. It is now considered a contactless state.

The developing units 121 and 122 are detachably attached to the copying machine main body 1, and the color of the toner contained in these developing units 121 and 122 is determined by, for example, a It is set by the connection status of multiple bins of the connector.

On the other hand, sheets of paper (material to be transferred) are taken out one by one from the selected upper paper feed cassette 131 or lower paper feed cassette 132 by feed rollers 14r, 142 and roller pairs 151, 152, and are taken out one by one by paper guide paths 161, 162. The photosensitive drum 10 is guided to a pair of registration rollers 17 through which the photosensitive drum 10 is guided to a transfer section in synchronization with the rotation of the photosensitive drum 10 . here,
The paper feed cassettes 131 and 132 are detachably provided at the lower right end of the main body 1, and one of them can be selected from the operation panel 30.

Further, the cassette size of each of the paper feed cassettes 131 and 132 is detected by cassette size detection switches 601 and 602, respectively. The cassette size detection switches 601 and 602 are composed of a plurality of microswitches that are turned on and off according to the insertion of cassettes of different sizes. Further, a manual feed guide 13a is provided on the upper surface of the paper feed cassette 131, and the paper manually inserted through the manual feed guide 13a is guided to the roller pair 151 by a delivery roller 14a, and then , the paper is transported in the same way as the paper fed from the paper feed cassette 131.

On the other hand, the paper sent to the transfer section comes into close contact with the surface of the photoreceptor drum 10 at the transfer charger 18, so that the toner image on the photoreceptor drum 10 is transferred by the action of the charger 18. . This transferred paper P is transferred to the peeling charger 1
The transferred image is electrostatically separated from the photoreceptor drum 10 by the action of step 9, is conveyed by a conveyor belt 20, and is sent to a fixing roller 21 as a fixing device provided at the end of the conveyor belt. It will be established. After fixing, the paper is discharged to a tray 25 outside the main body 1 by a pair of delivery rollers 22.

Further, after the photosensitive drum 10 has been transferred, residual toner on the surface thereof is removed by a cleaner 26, and residual images are erased by a static elimination lamp 27, so that the photosensitive drum 10 returns to its initial state. Note that 29 is a cooling fan for preventing the temperature inside the main body 1 from rising. Further, the exposure lamp 4,
The mirror 5 is provided on the first carriage 411, and the mirror 6
．． 7 is provided in the second carriage 412.

On the other hand, the first carriage 411 is provided with a spot light source 131 that is movable in a direction perpendicular to the moving direction of the first carriage 411. This spot light source 131
is provided with a light-emitting element that irradiates the document table 2 with a spotlight, and by means of this spotlight, it is possible to specify, for example, the erasing range of the document.

Furthermore, an erasing array 150 in which a plurality of light emitting elements are arranged along the longitudinal direction of the photosensitive drum 10 is provided between the charging charger 11 of the photosensitive drum 10 and the exposure section Ph.
is provided, and when performing partial erasure of a document image, the light emitting elements constituting the erasure array are turned on corresponding to the erasure area designated by the spot light source 131, for example, and the photoreceptor drum 10 is charged. It is designed to remove. Therefore, the part where the charge is removed is
Thereafter, in the exposure section Ph, no electrostatic latent image is formed even if slit exposure is performed, so that the original image is erased.

The exposure lamp 4 includes, for example, as shown in FIG.
A heater 40 serving as a heating means is wound around the outer peripheral surface excluding the light irradiation surface 4a of the document, and a thermistor 45 serving as a detection means is attached to the outside of the heater 40.

That is, the heater 40 is controlled so that the exposure lamp 4 is heated to obtain an appropriate temperature, that is, a necessary amount of light. Furthermore, the thermistor 45 detects the heating temperature of the heater 40, thereby detecting the tube wall temperature of the exposure lamp 4, which increases in accordance with this heating temperature.

FIG. 1 shows the main parts of the electric circuit. The thermistor 45 detects the temperature of the heater 40 and supplies a detection signal corresponding to the detection result to the comparison circuits 43 and 44. This comparison circuit 43 compares the stored first setting value for controlling the heater 40 and the detection signal from the thermistor 45, and supplies the comparison result to the heater control circuit 42. This heater control circuit 42 is, for example, a solid state
It is constituted by a relay, and is configured to control energization to the heater 40 according to the comparison result from the comparison circuit 43. Further, the comparison circuit 44 compares the stored second setting value (predetermined value) for controlling the exposure lamp 4 with the detection signal from the thermistor 45, and transmits the result of this comparison to the exposure lamp control circuit 33. supply to. The exposure lamp control circuit 33 controls the lighting of the exposure lamp 4 in accordance with the comparison result from the comparison circuit 44, that is, it controls the energization of the heater 4o in accordance with a signal supplied from a control section that does not indicate during return operation. By controlling the n-light lamp 4, the n-light lamp 4 is heated according to the first set value.

The exposure lamp control circuit 33 controls the lighting of the exposure lamp 4 in response to a signal supplied from a control section (not shown) during a copying operation, thereby irradiating the document with light during its reciprocating movement. .

In the above configuration, for example, when the power (not shown) of the copying machine main body 1 is turned on, the heater system circuit 42
The heater 40 is activated in response to a signal from a control unit (not shown).
Controls energization to. Thereby, the heater 40 heats the exposure lamp 4 according to the first setting value stored in the comparison circuit 43.

Then, by heating the heater 4o, the tube wall temperature of the exposure lamp 4 is raised to a temperature corresponding to the first set value, for example, about 30 degrees to 50 degrees.

In this state, when the copy key (not shown) on the operation panel 30 is operated, the exposure lamp 4, mirror 5, 6, .
7 and the registration roller pair 17 to scan the original and transport the paper, the developing device 122, the stripping charger 19, the fixing roller pair 21, the cleaner 26, and the static elimination lamp 27 The copying operation described above is performed by controlling the following. At this time, the exposure lamp control circuit 33 controls the energization of the exposure lamp 4 in accordance with a signal from a control section (not shown), thereby lighting the exposure lamp 4 during the reciprocating movement. As a result, the exposure lamp 4 irradiates the document with the amount of light necessary for exposure scanning.

On the other hand, the temperature of the heater 40 is detected by the thermistor 45, and the temperature detected by the thermistor 45 of the heater 4o is determined by the comparison circuit 43 to a first set value,
For example, if it is determined that the temperature exceeds 50 degrees, the heater control circuit 42 is controlled to prevent the heater 40 from being energized. As a result, the heater 40 is turned off and the tube wall temperature of the exposure lamp 4 is controlled.

Also, when scanning the document (during reciprocating movement), the thermistor 4
When the comparison circuit 44 determines that the detected temperature of the heater 40 by the exposure lamp 5 exceeds the second set value, for example 60 degrees, the exposure lamp control circuit 33 is controlled to control the energization of the exposure lamp 4. As a result, the exposure lamp 4 is turned off during the backward movement of scanning, and an increase in tube wall temperature due to self-heating of the exposure lamp 4 is suppressed.

According to the above embodiment, the temperature of the tube wall of the exposure lamp is determined from the heating temperature of the heater, and the detected temperature exceeds the limit temperature at which the amount of light necessary for scanning an original, for example, can be obtained. or when the temperature approaches the limit temperature at which the required amount of light can be obtained, the exposure lamp is turned off during the return movement of the exposure scan. This makes it possible to suppress an increase in tube wall temperature due to self-heating of the exposure lamp. Therefore, the temperature of the exposure lamp can be prevented from exceeding the limit temperature, and the required amount of light can always be obtained. Therefore, it is possible to always obtain a good transferred image of the same quality. Furthermore, since the exposure lamp can be driven at an appropriate temperature, the lamp life can be extended.

That is, by turning off the fluorescent lamp during the backward movement of document scanning, it is possible to suppress an increase in the tube wall temperature due to self-heating of the fluorescent lamp, and it is possible to prevent a decrease in the amount of light due to an increase in humidity.

Note that although the above embodiment has been described using a copying machine as an example, the present invention is not limited to this and can be applied to, for example, an image scanner or a facsimile.

Further, in the above embodiment, the case where the application is applied to a copying machine with a fixed document table has been described, but the invention is not limited to this. For example, by fixing the optical system such as an exposure lamp and moving the document table, Needless to say, the present invention can also be applied to a copying machine with a movable document table that exposes and scans a document.

It goes without saying that various other modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an exposure apparatus that can prevent a decrease in the amount of light due to a rise in temperature and can always obtain the required amount of light.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, and FIG. 1 is a block diagram schematically showing an electric circuit of an exposure apparatus of the invention;
Figures 2 and 3 each show the configuration of a two-color copying machine, with Figure 2 being a perspective view of the exterior, Figure 3 being a side sectional view, and Figure 4 schematically showing the configuration of the exposure lamp. The cross-sectional view shown in FIG. 5 is a temperature characteristic diagram showing changes in the tip of the fluorescent lamp. 1... Copying machine main body, 4... Exposure lamp, 10...
Photosensitive drum, 11... Charging charger, 121...
First developer, 122...Second developer, 18...
Transfer charger, 30... Operation panel, 33... Exposure lamp control circuit, 40... Heater, 42... Heater control circuit, 43.44... Comparison circuit, 45... Thermistor. Applicant's agent Patent attorney Suzue Takehiko J421

Claims (4)

[Claims] (1) A light source that irradiates light onto an object to be read, a heating means that heats the light source, a detection means that detects the temperature of the light source, and a temperature of the light source detected by the detection means that reaches a predetermined value. An exposure apparatus comprising: a stop means for stopping light irradiation by the light source during a return movement of exposure scanning when the exposure exceeds the limit. (2) The stopping means is configured to stop the light irradiation by the light source during the return movement of the exposure scan when the temperature of the light source exceeds a second set value that is higher than the first set value that controls the heating means. An exposure apparatus according to claim 1, characterized in that: (3) The exposure apparatus according to claim 1, wherein the light source is constituted by a fluorescent lamp. (4) The exposure apparatus according to claim 1, wherein the detection means detects the tube wall temperature of the fluorescent lamp from the temperature of the heating means.